"The decision by Trump on Al-Quds (Jerusalem) makes it legitimate to strike the American forces in Iraq," Al-Nojaba militia chief Akram al-Kaabi said in a statement.

The Shiite group, established in 2013 and supported by Iran&39;s Revolutionary Guards, numbers around 1,500 fighters and is part of the Hashed al-Shaabi (Popular Mobilisation) auxiliary force that has fought alongside the army against the Islamic State group.

The US has thousands of troops stationed in Iraq to help in the fight against IS.

Officially, the Pentagon says it has 5,262 personnel in the country, but other figures released by the US military have put the number at almost 9,000.

Trump&39;s move to end decades of careful US policy on Jerusalem has sparked a storm of condemnation around the globe, both from Washington&39;s traditional allies and its international foes.

Iraqi Foreign Minister Ibrahim al-Jaafari summoned the US ambassador in the country to protest the shift, while powerful Shiite cleric Moqtada al-Sadr, who heads his own militia, demanded the closure of the American embassy in Baghdad and warned that "we can reach Israel through Syria".

The spiritual head of Iraq&39;s Shiites Grand Ayatollah Ali Sistani in a statement "denounced and condemned the American decision that injures the feelings of hundreds of millions of Arabs and Muslims".

"This will not change the fact that Jerusalem is an occupied territory that needs to be returned to its legitimate Palestinian owners," he said.